蒸汽流场对凝汽器汽阻的影响

基于两相流的有关理论,分析了凝汽器喉部出口蒸汽流场对凝汽器汽阻影响的机理。指出采用均流装置使300MW机组凝汽器喉部出口蒸汽流场趋于均匀以后,可以减小汽阻、降低排汽压力。为提高机组的经济性提供了新的途径。     

超临界600MW机组回热系统变工况对发电煤耗影响的定量分析

以某600MW超临界凝汽式机组为例建立仿真模型,在VWO工况、THA工况、75%THA工况和50%THA工况下模型的计算值与设计值的相对误差小于0.08%。运用模型进行了不同工况下加热器效率、加热器切除、除氧器排汽连续运行、给水泵汽轮机汽源变化4种回热系统变工况对机组发电煤耗影响的定量分析。结果表明,不同负荷工况下,2号高压加热器效率对机组发电煤耗影响更大,其次是1号高加、3号高加、5号低加至8号低加;高压加热器切除对机组发电煤耗影响最大,5号低加至8号低加切除对发电煤耗的影响逐渐减小;除氧器排汽量相同时,机组发电功率越低,对机组发电煤增量的影响越大;给水泵汽轮机采用辅助联箱蒸汽作为汽源时,机组发电功率越高,对机组发电煤耗增量的影响越大。     

高压加热器疏水采用汽液两相流的经济性分析

探讨了江西新余发电有限责任公司2号机高加疏水系统改造前后的运行状况,简介汽液两相流自调节装置的原理,并对系统改造前后的经济性进行了定量计算。     

汽液两相流自调节液位控制器在高压加热器上的应用

通过汽液两相流自调节液位控制器在解决汽轮机高压加热器无水运行状况的成功应用实例,找出了无水运行状况的原因,介绍了汽液两相流自调节液位控制器原理、特点及安装要点,并分析了应用技术经济效果。     

提高汽轮机压力匹配器效率的新技术

介绍提高压力匹配器运行效率的最新研究成果,可以将压力匹配器的运行效率提高20%~30%。提高压力匹配器运行效率主要技术是安装工况调节器和吸入蒸汽冷却器。     

直接空冷凝汽器压力特性的耦合计算与分析方法

传统的空冷凝汽器特性计算方法中认为汽轮机低压缸排汽焓保持不变,但实际上空冷凝汽器压力的变化也会反向影响排汽焓,进一步对凝汽器压力产生耦合影响。基于空冷凝汽器背压与排汽焓的耦合分析,提出了一种基于迭代算法的空冷凝汽器模型与分析方法。通过对某600MW机组空冷凝汽器的计算分析,得出其在不同汽轮机负荷、环境温度工况下凝汽器压力的变化特性曲线,定量分析了汽轮机负荷和环境温度变化对凝汽器压力影响的对应关系,对空冷机组的安全经济运行具有一定的参考价值。     

基于反问题理论的汽液两相上升流流型预测与实验研究

汽液两相流流型的测量在两相流研究中占有重要地位。应用均相流模型建立了圆管内汽液两相上升流压力分布,基于反问题理论反演了汽液两相的物性参数,将反演结果与流型图结合,精确地预测了管内流型,计算结果与实验结果进行了对比,误差小于5%。提出的反演流型的方法,可以推广到水平管、螺旋管,为工程上的汽液两相流设备安全性分析、稳定性分析等提供了一种简单可靠的技术方法。     

汽液两相流直接接触升压加热装置性能的研究

针对汽液两相流混合喷射直接接触实现加热和升压两种目的的装置进行了理论和实验研究,利用质量,动量,能量守恒建立了汽液两相流直接接触加热升压装置的或压性能和加热性能数学模型,根据理论分析和实验数据得出了其性能的计算方法和参数对升压性能的影响规律,为该装置的工业应用奠定了理论基础。     

液-汽引射器内液汽混合过程压力及汽液分布特性研究

为了明确液-汽引射器在工作过程中压力及液汽分布特性,采用混合多相流模型及标准k-ε湍流模型,建立了液-汽引射器三维数值计算模型,对液-汽引射器内部的压力及液汽流动状态进行了分析模拟,得到了不同工作流体参数下引射器内部压力及汽液分布规律。研究表明:沿引射器水平中轴线方向,压力及汽相体积分数随工作流体压力的增大而减小,随工作流体温度及流量的变化基本不变;沿引射入口轴线方向,吸入室的压力随工作流体压力的增大而减小,随工作流体温度及流量的变化几乎不变;沿引射入口轴线方向,汽相体积分数随工作流体压力及温度的变化较小,随工作流体流量的增大而增大。研究将有助于掌握液汽引射器内部压力及汽相体积分数的变化规律,有助于引射器的科学设计和运行。     

中小型热电厂的几项节能措施

从设计角度列举了中小型热电厂的几项节能措施 ,目的是从设计上把握好节能这一环节 ,提高热电效率 ,增加经济效益     

Performance enhancement in coal fired thermal power plants. Part II: steam turbines

This paper presents the results of the performance enhancement study on 22 coal fired thermal power stations of capacities 30–500 MW. The oldest units (30 MW) have served for 33yr and the newer units (500 MW) have been in operation since 7yr. The turbine efficiencies are in the range 31·00–41·90% as compared to the design range of 34·80–43·97%. The isentropic efficiencies are in the range 74·13–86·40% as compared to design values of 83·20–89·10%. Considerable scope for efficiency improvement through low cost solutions: operational optimization, capital overhaul, simple modifications, etc., exists for all classes of units. The efficiencies can be restored to their design values. The developments in turbines over the last quarter of this century which have led to improved isentropic and thermal efficiencies must be adopted for existing units through retrofits, upgrades and revamps. The turbine efficiencies can be improved to 38·0% for 30 MW units and to 47% for 500 MW units. The maximum potential is for improvement in 210 and 500 MW units followed by 110 and 120 MW units. The potential for 30 and 62·5 MW units is rather limited because of their low capacity share, lack of interest in manufacturers to sell spares (because of the low volume of requirement) and large pay back periods for modernisation schemes. Copyright © 1999 John Wiley & Sons, Ltd.     

冷却水流程数对凝汽器热力性能的影响

电站凝汽器可以设计成冷却水双流程和单流程。利用自行开发的凝汽器工作特性数值模拟软件PPOC3．0模拟和分析了冷却水流程数对电站凝汽器的热力性能的影响,结果表明单流程凝汽器比双流程凝汽器有更高的热负荷和更小的汽侧阻力。     

电厂主蒸汽流量测量与计算方法分析比较

介绍了目前获取发电机组主蒸汽流量的几种常用方法,对它们进行了分析比较,指出影响主蒸汽流量测量精度的几个主要因素,并提出了提高发电机组主蒸汽流量测量精度的相应对策。     

凝汽器喉部内置低压加热器的合理布置研究

从减小凝汽器喉部汽阻和保证喉部流动的稳定性和均匀性出发,通过计算机数值模拟,对内置低压加热器的布置方式进行了优化研究,综合分析了低压加热器不同布置高度对流动阻力及出流均匀性和稳定性的影响,获得了凝汽器喉部设计过程中具有一定指导意义的结果。     

Comparative studies of augmentation in combined cycle power plants

The attractive features of a combined cycle (CC) power plant are fuel flexibility, operational flexibility, higher efficiency and low emissions. The performance of five gas turbine‐steam turbine (GT‐ST) combined cycle power plants (four natural gas based plants and one biomass based plant) have been studied and the degree of augmentation has been compared. They are (i) combined cycle with natural gas (CC‐NG), (ii) combined cycle with water injection (CC‐WI), (iii) combined cycle with steam injection (CC‐SI), (iv) combined cycle with supplementary firing (CC‐SF) and (v) combined cycle with biomass gasification (CC‐BM). The plant performance and CO₂ emissions are compared with a change in compressor pressure ratio and gas turbine inlet temperature (GTIT). The optimum pressure ratio for compressor is selected from maximum efficiency condition. The specific power, thermal efficiency and CO₂ emissions of augmented power plants are compared with the CC‐NG power plant at the individual optimized pressure ratios in place of a common pressure ratio. The results show that the optimum pressure ratio is increased with water injection, steam injection, supplementary firing and biomass gasification. The specific power is increased in all the plants with a loss in thermal efficiency and rise in CO₂ emissions compared to CC‐NG plant. Copyright © 2013 John Wiley & Sons, Ltd.     

凝汽器内低压加热器对流动与传热特性影响的数值分析

以一台３００ＭＷ汽轮机凝汽器为研究对象,用数值模拟的方法了凝汽器内管速上方低压加热器的布置对凝汽器工作特性的影响,计算结果表明,低加对凝汽器的平均传热系数、平均汽阻及抽汽口处未凝结汽量都有较大的影响,凝汽器特性随低加位置的变化也相应地变化。     

考虑真空泵汽蚀特性的300MW汽轮机凝汽器特性曲线

现有的300MW机组凝汽器特性曲线没有考虑到水环真空泵汽蚀特性对凝汽器运行特性的影响,不能准确反映凝汽器的运行状态。文中首先对300MW机组凝汽器水环真空泵的汽蚀特性进行了分析,并给出了汽蚀的判断方法以及汽蚀余量的表达式。然后,以国产引进型300MW汽轮机凝汽器为例,计算汽轮机负荷及冷却水温度对水环真空泵汽蚀余量的影响。最后,给出了考虑水环真空泵汽蚀特性后的300MW机组凝汽器特性曲线及其绘制方法,该曲线能较准确地反映凝汽器的运行特性。     

Two-phase air-water flow in micro-channels: An investigation of the viscosity models for pressure drop prediction

Adiabatic two-phase air-water flow is experimentally studied in this work. Two channels, made of fused silica, with different diameters of 0.53 and 0.15 mm are used as test sections. The void fraction data for both tubes are obtained by image analysis. For the larger channel, the void fraction is found to be a linear relationship with the volumetric quality. In the case of the smaller one, however, the non-linear void fraction is obtained. The measured frictional pressure drop data are compared with the predictions regarding the homogeneous flow assumption. Several well-known two-phase viscosity models are subsequently evaluated for applicability to micro-channels.     

Influence of cooling water temperature on the efficiency of a pressurized‐water reactor nuclear‐power plant

In this study, the influence of the cooling water temperature on the thermal efficiency of a conceptual pressurized‐water reactor nuclear‐power plant is studied through an energy analysis based on the first law of thermodynamics to gain some new insights into the plant performance. The change in the cooling water temperature can be experienced due to the seasonal changes in climatic conditions at plant site. It can also come into the question of design processes for the plant site selection. In the analysis, it is considered that the condenser vacuum varies with the temperature of cooling water extracted from environment into the condenser. The main findings of the paper is that the impact of 1°C increase in temperature of the coolant extracted from environment is predicted to yield a decrease of ～0.45 and ～0.12% in the power output and the thermal efficiency of the pressurized‐water reactor nuclear‐power plant considered, respectively. Copyright © 2005 John Wiley & Sons, Ltd.     

电热水器替代电厂蒸汽的节能分析

通过对某公司目前使用的电热水器与之前使用的电厂蒸汽进行对比,经过系统的计算得出具体数据,并将运行费用及设备投资进行对比,从节能角度指出电热水器替代电厂蒸汽的合理性、经济性及可行性。